It is important to understand the influence of the parasitic varroa mites that we have in nearly all colonies all over Europe.
INSIGNIA uses the honeybees as bioindicators of our surroundings, of the environment. We want to understand what is going on in our environment, about the pollution, the farmers spraying, etc. But then we also need to understand the beekeepers. What are they doing in the colonies ? They need to treat against the varroa mites, otherwise the colonies will die within a few years.
Varroa mites double up the number of mites during the months of brood production in the colonies, which is typically during summer. It decreases during late fall and has low or no production in midwinter. They can only multiply on sealed brood. You can say that one varroa mite in the spring will multiply to 100 mites. If beekeepers do not control varroa, then varroa is getting out of control. With the bite of the varroa mites on the honeybees, they also spread viruses. The bee colonies will collapse when the mite number get up to something between 2000-5000 mites. That means that if a colony starts out with just 20 mites in the spring, they could collapse at the end of the season.
Several drugs have been developed to fight varroa. They are highly effective, but also have the risk of getting unwanted substances into the honey and mites producing resistance towards the substance. On the other side, we have organic methods allowed in organic beekeeping and used by many beekeepers in conventional beekeeping. In the INSIGNIA apiaries in Denmark, this year we removed drone brood in the spring (drone brood so to say catches varroa mites behind the wax sealings), we applied thymol or formic acid after the last honey harvest (around 1st August) and then in December we treated the colonies with oxalic acid trickling. This is a mixture of sugar and water in a 3.2 % oxalic acid solution. It works like a contact substance and varroa is very sensitive to this trickling. The tricky thing is that it only kills the mites on the bees and not behind the sealed brood. In Denmark the amount of sealed brood is on its lowest around Christmas. This proves to be very effective.
So, our recommendation for beekeepers is: On Christmas eve, when you need a small break from the heavy Christmas activities, go to your bees and wish them Merry Christmas with a varroa treatment via oxalic acid trickling. This is the best gift you can give your bees.
Pictures are from INSIGNIA apiary 1 on the 24th December around 15.00.
Happy new year, with a low load of varroa
Flemming Vejsnæs